The International Space Station (ISS) has been moved to a higher orbit to avoid the danger of a collision with a floating tool dropped by a spacewalking astronaut.

The change was made by the space shuttle Discovery, which is currently docked to the ISS about 380 kilometres (236 miles) above the surface of the Earth.

On Wednesday, mission controllers ordered shuttle commander James Wetherbee to fire Discovery's thrusters, moving the two craft about four kilometres (2.5 miles) further up and well clear of the piece of space junk.

Nasa later admitted that it was a false alarm, saying their readings of the object's path had been wrong.

The conjoined platform and orbiter are moving at a speed of about eight kilometres (five miles) per second. Any collision with the shoebox-sized tool could have punched a hole in the space station's walls, leading to a rapid drop in pressure.

The errant piece of equipment was lost by astronaut James Voss near the start of a nine-hour spacewalk on Sunday.

Return journey

Like all orbiting debris, which ranges from bolts to large fuel tanks, the tool was followed by trackers on the ground who predicted it would pass within about 70 metres (200 feet) of the ISS complex.

Discovery is in orbit to deliver a relief crew, new supplies, equipment and experimental racks for the Destiny laboratory.

The gear was carried aloft by the shuttle in the Leonardo logistics module. The Italian-built module was attached to the ISS to be emptied and is now being filled with rubbish, luggage and equipment for the return journey to Earth.

The new platform crew, known as Expedition Two, are continuing to go through handover notes with the departing Expedition One.

The crews were awoken on Wednesday with the song Should I Stay, or Should I Go? by The Clash. It was played for returning Expedition One commander Bill Shepherd - a request from his wife, Beth.